Added github action to keep legacy master branch up to date with late…

…st main

.github/workflows/main-to-master.yml

@@ -0,0 +1,19 @@
+name: Build
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    pernmissions:
+      contents: write
+    steps:
+    - uses: actions/checkout@v4
+    - name: Update legacy master
+      uses: ad-m/github-push-action@master
+      with:
+        github_token: ${{ secrets.GITHUB_TOKEN }}
+        branch: ${{ github.ref }}